Nitrogen and phosphorus fertilization of Sparganium eurycarpum and Typha glauca stands, Eagle Lake, Iowa

In 1979 and 1980, NH(,4)NO(,3) and (NH(,4))(,2)HPO(,4) were applied to surface water of a prairie marsh, Eagle Lake, Iowa, to determine the impact of nitrogen and phosphorus loading in a natural wetland on water chemistry and on emergent plant production and decomposition. Nitrogen and phosphorus fertilization of surface water in 1979 caused increases of NH(,4)-N (+144%), NO(,3)-N (+291%), and PO(,4)-P (+47%) in 15-cm deep interstitial water. In 1980, fertilization caused increases in NH(,4)-N (189%), PO(,4)-P (+60%), and the non-PO(,4)-P fraction of total phosphorus (+50%) at the same depth;Typha glauca and Sparganium eurycarpum responded to fertilization with increased concentrations of nitrogen in the shoots (+30 to 34% for Sparganium and +7% to 14% for Typha) and roots-rhizomes (+25% for Sparganium and +38% for Typha in 1980); increased shoot density in 1980 (+20% for Sparganium and +30% for Typha), and shoot production in 1980 (+57% for Sparganium and +19% for Typha). Root-rhizome production was not altered by fertilization;Sparganium shoot litter with an initial nitrogen concentration of 1.41% lost 27% more dry weight over a 505-day period than did Sparganium with an initial nitrogen concentration of 0.59%. Typha shoot litter with an initial nitrogen concentration of 0.55% lost 2% more dry weight during 505 days than Typha tissues with an initial nitrogen concentration of 0.48%. Application of nitrogen and phosphorus to marsh surface waters did not alter the rate of Sparganium or Typha shoot and root-rhizome decomposition;Nitrogen-rich Sparganium shoot tissue was a net exporter of nitrogen through 505 days of decomposition (-50% of original N quantity) and Typha shoot tissue was a net exporter of nitrogen through only 350 days of decomposition (-14%). Quantities of nitrogen increased for Sparganium (+31%) and decreased for Typha (-10%) shoot tissues under unfertilized conditions and increased 35% for both species with fertilization over 505 days. Under unfertilized conditions, phosphorus quantities decreased for Sparganium (-2%) and increased for Typha (+25%) shoot tissues over 505 days. Phosphorus quantities increased in Sparganium (+7%) and Typha (+121%) shoot tissues with fertilization over 505 days. Root-rhizome litter consistently lost nitrogen throughout the 505-day sequence under unfertilized and fertilized conditions (-24 to 54% for the two species)

Is technical analysis in the foreign exchange market profitable? a genetic programming approach

Using genetic programming techniques to find technical trading rules, we find strong evidence of economically significant out-of-sample excess returns to those rules for each of six exchange rates, over the period 1981-1995. Further, when the dollar/deutschemark rules are allowed to determine trades in the other markets, there is a significant improvement in performance in all cases, except for the deutschemark/yen. Betas calculated for the returns according to various benchmark portfolios provide no evidence that the returns to these rules are compensation for bearing systematic risk. Bootstrapping results on the dollar/deutschemark indicate that the trading rules are detecting patterns in the data that are not captured by standard statistical models.Programming (Mathematics) ; Foreign exchange

Wind-Tunnel Tests of an NACA 44R-Series Tapered Wing with a Straight Trailing Edge and a Constant-Chord Center Section

As part of a general investigation in the NACA 19-foot pressure tunnel to determine stall characteristics and effectiveness of high-lift devices on wings of various sections, tests were made of a tapered. wing having NACA 44R-series airfoil sections. Lift, drag, pitching-moment, and stall characteristics were determined at a Reynolds number of 4,850,000 for the plain wing and for the wing with partial-and with full-span split flaps. The stall progressed slowly over The plain wing; a gradual loss of lift for angles of attack up to and beyond that for the maximum lift coefficient resulted. As Compared with the stall of the plain wing, the initial stall of the wing with either partial-span or full-span flaps deflected occurred at a higher angle of attack and the stall progressed much more rapidly. The maximum lift coefficients at a Reynolds number of 4,850,000 were 1.35 for the plain wing, 2.25 for the wing with partial-span flaps at 60 deg, and 2.67 for the wing with full-span flaps at 60 deg. The positions of the aerodynamic center, in terms of mean chords back of the leading edge of the root section, were approximately 0.458 with no flaps, 0.483 with partial-span flaps at 60 deg, and 0.498 with full-span flaps at 60 deg

Information technology in the MBA curriculum: The Case for relevant topics

While technology can be used as an important competitive tool for organizational survival and growth, many graduate business programs have been unclear in their delineation of which topics should be included within their core IT/IS MBA course. A total of 311 1st year, 2nd year, executive MBA student and faculty were surveyed as to which technology topics they believed were most important in an IT/IS core. MBA course Strategic use of MIS , Management\u27s Information Needs and E-Business were rated as the top three most important topics that should be included in the core IT/IS course. Conversely Artificial Intelligence , MIS Hardware , and Ethics and MIS were rated as the three least important topics. These survey results indicate that the desired focus for an IT/IS core course should be on the strategic use of technology to support decision-making rather than on specific technology topics. Interpreted in another way, the results suggest that MBA an faculty would prefer that the IT/IS core course be structured with a managerial or business focus versus a technical focus within their MBA curriculum

The BsaHI restriction-modification system: Cloning, sequencing and analysis of conserved motifs

<p>Abstract</p> <p>Background</p> <p>Restriction and modification enzymes typically recognise short DNA sequences of between two and eight bases in length. Understanding the mechanism of this recognition represents a significant challenge that we begin to address for the BsaHI restriction-modification system, which recognises the six base sequence GRCGYC.</p> <p>Results</p> <p>The DNA sequences of the genes for the BsaHI methyltransferase, bsaHIM, and restriction endonuclease, bsaHIR, have been determined (GenBank accession <ext-link ext-link-type="gen" ext-link-id="#EU386360">#EU386360</ext-link>), cloned and expressed in <it>E. coli</it>. Both the restriction endonuclease and methyltransferase enzymes share significant similarity with a group of 6 other enzymes comprising the restriction-modification systems HgiDI and HgiGI and the putative HindVP, NlaCORFDP, NpuORFC228P and SplZORFNP restriction-modification systems. A sequence alignment of these homologues shows that their amino acid sequences are largely conserved and highlights several motifs of interest. We target one such conserved motif, reading SPERRFD, at the C-terminal end of the bsaHIR gene. A mutational analysis of these amino acids indicates that the motif is crucial for enzymatic activity. Sequence alignment of the methyltransferase gene reveals a short motif within the target recognition domain that is conserved among enzymes recognising the same sequences. Thus, this motif may be used as a diagnostic tool to define the recognition sequences of the cytosine C5 methyltransferases.</p> <p>Conclusion</p> <p>We have cloned and sequenced the BsaHI restriction and modification enzymes. We have identified a region of the R. BsaHI enzyme that is crucial for its activity. Analysis of the amino acid sequence of the BsaHI methyltransferase enzyme led us to propose two new motifs that can be used in the diagnosis of the recognition sequence of the cytosine C5-methyltransferases.</p

Wind-Tunnel Investigation of an NACA Low-Drag Tapered Wing with Straight Trailing Edge and Simple Split Flaps, Special Report

An investigation was conducted in the NACA 19-foot pressure wind tunnel of a tapered wing with straight railing edge having NACA 66 series low-drag airfoil sections and equipped with full-span and partial-span simple split flaps. The airfoil sections used were the NACA 66,2-116 at the root and the 66,2-216 at the tip. The primary purpose of the investigation was to determine the effect of the split flaps on the aerodynamic characteristics of the tapered wing. Complete lift, drag, and pitching-moment coefficients were determined for the plain wing and for each flap arrangement through a Reynold number range of 2,600,000 to 4,600,000. The results of this investigation indicate that values of maximum lift coefficient comparable to values obtained on tapered wings with conventional sections and similar flap installations can be obtained from wings with the NACA low-drag sections. The increment of maximum lift due to the split flap was found to vary somewhat with Reynold number over the range investigated. The C(sub L)max of the wing alone is 1.49 at a Reynolds number of 4,600,000; whereas with the partial-span simple split flap it is 2.22 and with the full-span arrangement, 2.80. Observations of wool tufts on the wing indicate that the addition of split flaps did not appreciable alter the pattern of the stall; even though the stall did occur more abruptly than with the wing alone

Wind-Tunnel Investigation of an NACA 66,2-216 Low-Drag Wing with Split Flaps of Various Sizes, Special Report

An investigation was conducted in the NACA 19-foot pressure wind tunnel of a rectangular wing having NACA 66, 2-216 low-drag airfoil sections and various sizes of simple split flaps. The purpose of the investigation was, primarily, to determine the influence of these flap installations on the aerodynamic characteristics of the wing. Complete lift, drag, and pitching-moment characteristics were determined for a range of test Reynolds numbers from about 2,600,000 to 4,600,000 for each of the installations and for the plain wing. The results of this investigation indicate that values of maximum lift coefficient similar to those of wings with conventional airfoil sections and split flaps can be expected of wings having the NACA 66,2-216 low-drag sections. The increment of maximum lift due to the split flap was found to be practically independent of the Reynolds number over the range investigated. The optimum split flap on the basis of maximum lift appears to have a chord about 20% of the wing chord and a deflection of 60 degrees. The C(sub L) max of the wing with the 0.20c partial-span flap deflected 60 degrees is 2.07 at a Reynolds number of 4,600,000 while with the full-span flap it is approximately 2.53; the increment of the maximum lift coefficient due to the flap is approximately proportional to the flap span. Although the addition of a split flap tends to hasten the stall and to cause it to occur more abruptly, little change in pattern is evidenced by observations of the behavior of wool tufts on the wing